Exam 3 solution

# Exam 3 solution - PHSX 114 Exam #3; ode number 4 2 1. (10...

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Unformatted text preview: PHSX 114 Exam #3; ode number 4 2 1. (10 points) A disk. of rais 0.5 is spinning at 70 revolutions per minute. What is the tangential velocity of a point on the rim of the disk? a) 114 m/s b) 35 m/s _,, - —-— ‘ . c) 0.58m/s U “‘ 2” Y ‘3 an. 3670M : 2m osmno m 623? =3W/é ______ 60 6 . 2. (10 points) A car is roundng a curve at a constant speed of 42.0 m/s. The centripetal acceleration on the car is 3.70 m/sz. What is the radius of the curve? 2 a) 6530 m 1 1) b) 11.3 m 1 c) 155 m 1 QR M D a. 31» -,—. ‘5 : . 4 ’7 7 M e) . m a 3 31 ‘ 3. (10 points) Calculate the force of Earth’s gravity on a spacecraft 2 Earth radii above the Eaith’s surface if its mass is 1350 kg. (Radius of the Earth=6.37X106 m) r: -—: C‘IMem = GME m zima c)58N 3R“ 2 3 ‘ d)404N L b R; Ci at e)1936N ___._. _l_,( 550133 :4 \$8331- » WHOM 4. (10 points) A planet has six times the mass of the Earth (Mass of the Earth=5.98x1024 kg) while the acceleration due to gravity on the planet’s surface is twice that on Earth. The rau g . the planet in terms of Earth’s radius, RE, is : (1 w " - + s - .' RE' A “WV/133 m on m (gmjm Oi g MR ‘ l m : 1: d)1/\/3ERE P a e"? we 6‘“ 6M . m e)1/3RE W : 1mg) t: G e L riblc‘nerh. regse%.ﬁ=wse 6 Re GME here ode meet . 6 “’- ﬁa— PHSX 114 Exam #3, code number 4 3 5. (10 points) A 55—kg woman stands on a spring scale in an elevator that moves. If the scale reading is 50% of her stationary weight (i.e., her weight when the elevator is at rest), the elevator is: A N m ~ w = mg (a) moving upward with constant speed of 0.5 m/s, \L OK 5 ‘ (b) moving downward with constant speed of 0.5 m/s, ' :5 W = 9 3m c n g -_- - - : .-. . u__ tant acceleration of 0.5 g, M6 _. 7 . J- “ ‘ (6)1nfree - "I ms—ZWKS—mq Q 2. ldommar‘o{ 6. (10 points) A ball is dropped from rest from a height of 4 In above the ground. The hall‘s velocity just before it hits the ground is v. As it falls, at what height above the 1 ground is the ball’s speed equal to 0.5V? Ignore air resistance. min. = lime: m5hti‘méU \ 2— WA szU) ‘ qut- 31";23L. 6““(2 U2?- 25in). :7 VIZ-31hr): 33m 7. (10 points) How much work must be done to stop a 1250—kg car traveling at 35 ? a)846,127J u, :2- BSWV.s w L: 0 1 b)6,395I ‘ (334,165; I W}: [l mu:_ glan I : Ji XIzSQICSAé\$Sm> i413l791] 2 W 1.76§.62s'3’. 8. (10 points) A 2.0 kg box of initial speed of v1=15 rn/s sliding on a frictionless ﬂat surface runs into a ﬁxed spring (k=850 N/m), which compresses a distance X to stop the box. d) X:0.54 m e) X: 0.84 m PHSX 114 Exam #3, code number 4 4 9. (10 points) How much power is needed to lift a 100 kg crate a vertical distance of 4 In in 20 seconds? M d 7_ _ (2)) isiggoww 2, [Cl 6 V\/ 10. (10 points) A block of mass 0.14 kg is shot across a horizontal table by a spring gun (assuming no friction inside the gun and no air resistance during the entire procedure). The gun’s spring has constant 3600 N/m and is initially compressed by 0.015 m. If the coefﬁcient of friction between the block and the table is 0.44, what horizontal distance does the block travel? 0 SWOT W 6% _ a; as law = em? 3; @5ng @ sled m were In e) 180m Wzﬂmgdzémkj: 1 ol :. al- Us” _ e- 1< >3 inst-W0 Extra credit problem (10 points): J“ 0 t m a M 0 “l ES *Cl'%§xoq3f ll. (10 points) A ball swings in a vertical circle of radius 0.78 In, If the velocity of the” 0‘6 7 m ball at the top of the circle is 3.0 m/s, What is its velocity at the bottom of the circle? Assume the tension and the weight are the only two forces acting. b) 3.9 III/S t u; m ..\. ..__. WU 0) ._ 55 r l 8 > 2_ l __.. _ - ﬁ l 2 6) \ t2.“ 3 M U; fl); 2 JCSEJIl-Cf—KﬁQ-Eg X 018‘“ "3-632 ...
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## This note was uploaded on 04/27/2009 for the course PHSX 114 taught by Professor Davis during the Spring '08 term at Kansas.

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Exam 3 solution - PHSX 114 Exam #3; ode number 4 2 1. (10...

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